Molecular Characterization and Functions of Fatty Acid and Retinoid Binding Protein Gene (Ab-far-1) in Aphelenchoides besseyi

Abstract

Rice white tip nematode, Aphelenchoides besseyi, is a kind of plant parasitic nematodes that cause serious losses in rice and many other crops. Fatty acid and retinoid binding protein (FAR) is a specific protein in nematodes and is related to development, reproduction, infection to the host, and disruption of plant defense reactions, so the inhibition of FAR function is the potential approach to control A. besseyi. The full-length of Ab-far-1 cDNA is 805 bp, including 546 bp of ORF that encodes 181 amino acids. Software analysis revealed that the Ab-FAR-1 was rich in α-helix structure, contained a predicted consensus casein kinase II phosphorylation site and a hydrophobic secretory signal peptide, but did not have glycosylation sites. The Ab-FAR-1 had 52% homology to Gp-FAR-1 protein. The Ab-FAR-1 and Gp-FAR-1 were grouped in the same branch according to the phylogenetic tree. Fluorescence-based ligand binding analysis confirmed that the recombinant Ab-FAR-1 (rAb-FAR-1) bound with the fluorescent analogues 11-((5-dimethylaminonaphthalene-1-sulfonyl) amino) undecannoic acid (DAUDA), cis-parinaric acid and retinol, but the oleic acid would compete with the binding site. Quantitative PCR (qPCR) was used to assess the expression level of Ab-far-1 at different development stages of A. besseyi, the highest expression was found in the females, followed by eggs, juveniles and males. Using in situ hybridization technique, Ab-far-1 mRNA was present in the hypodermis of juveniles and adults, the ovaries of females and the testes of males. When A. besseyi was treated with Ab-far-1 dsRNA for 48 h, the silencing efficiency of Ab-far-1 was the best and the number of nematodes on the carrot was the least. Thus FAR plays important roles in the development and reproduction of nematodes. This study is useful and helpful to figure out a new way to control the plant parasitic nematodes.

A Nematode Calreticulin, Rs-CRT, Is a Key Effector in Reproduction and Pathogenicity of Radopholus similis

“…In situ hybridization was performed as described elsewhere [13, 47]. After hybridization, the nematodes were examined by microscopy (Nikon 90i).…”

“…RNAi mediated by dsRNA soaking ( in vitro RNAi) has been developed as an effective tool for studying gene function in many plant nematodes and other organisms [8–13]. However, the silencing effect of in vitro RNAi on some genes in plant-parasitic nematodes is highly time-limited [11, 14].…”

The white-tip nematode, Aphelenchoides besseyi, exhibits an auxin-orientated behaviour affecting its migration and propagation

“…China. The nematodes were cultured on excised carrot (Daucus carota) and extracted using blender disks as described by Cheng et al (2013). The nematodes were surface-sterilised with deionised sterile water (Sun et a l, 2009) and stored at 4°C.…”

Structural characterization and localization analysis of the root-knot nematode Meloidogyne javanica fatty acid and retinol binding protein (Mj-FAR-1)

“…The spike in expression of Mj-far-1 in M. javanica second-stage juveniles observed at 3-5 days after infection, along with its abundant deposition in the apoplast during the sedentary stages, suggested a primary role for this effector protein in the early and late stages of the host-parasite interaction. Similarly, studies on the FAR protein of the rice whitetip nematode Aphelenchoides besseyi, Ab-FAR-1, demonstrated that treatment of A. besseyi with Ab-far-1 dsRNA results in reduced reproduction of A. besseyi nematodes on carrot (Cheng et al 2013).…”

“…Interestingly, group A has the highest sequence identity to FAR proteins from parasitic nematodes, among them the plant parasitic FAR proteins of Globodera pallida (Gp-FAR-1), Meloidogyne javanica (Mj-FAR-1) and Aphelenchoides besseyi (Ab-FAR-1) (Cheng et al 2013;Iberkleid et al 2013;Prior et al 2001). FAR proteins have also been extensively found in parasitic nematodes of humans and animals, including Ancylostoma caninum, Brugia malayi, Brugia pahangi, Ancylostoma ceylanicum, Acanthocheilonema viteae, Ascaris suum, Heligmosomoides polygyrus, Onchocerca gutturosa, Onchocerca dukei, Onchocerca ochengi, Loa loa, Wuchereria bancrofti, and Litomosoides sigmodontis (Basavaraju et al 2003;Bath et al 2009;Fairfax et al 2009;Garofalo et al 2002;Mei et al 1997;Nirmalan et al 1999).…”